Whitney HoustonOff the Wagon ...With the Help of Enablers

2/15/2012 11:45 AM PST

Whitney Houston -- Enablers Contributed to Alcohol Abuse

Whitney Houston was heavy into alcohol in the months before her death, and many of the people around her bent over backwards to accommodate her cravings for alcohol.

Sources who spent significant time with Whitney in the last few months tell us ... Whitney drank virtually every day leading up to her death.

We're told when she started shooting the movie "Sparkle" she was sober. In fact, Whitney's voice, we're told, was "phenomenal" and she would boast to people, "My voice is back!"

But after principal shooting, when Whitney went into the studio to dub various lines, we're told she was off the wagon.

We're told Whitney's immediate family -- and Bobby Brown -- became "extremely upset" because they believed the singer's friends were more than happy to accommodate her drinking whims whenever she wanted, even though it was apparent she had lost control.

As TMZ first reported, Whitney's family says authorities told them ... she may have died from a reaction to prescription drugs and alcohol. We know she drank alcohol shortly before her death, and we're told she typically took Xanax -- one of the drugs found in her room -- before a performance to calm her nerves, and she was scheduled to sing at Clive Davis' Grammy party.